Need to know how much ice you need to bring your water down to a suitable temperature for ice bathing?
Or how cold your bath is after you’ve added the ice?
To get answers, use the calculators below – available in Metric and Imperial (US). For an explanation of the Physics involved – scroll down to the bottom.
You can also read here for a full description of the health effects of ice baths.
Hints & Tips
Assumption #1: All the Ice Melts. If you want to simulate e.g. only half of the ice melts, then put half the amount of ice in the relevant field.
Assumption #2: No Heat is Added. In practice, you will warm up the water when you bathe, and some heat will be lost to the environment. For this reason the calculated temperature is a theoretical minimum and your bath will be a little warmer.
The Temperature Range for an Ice Bath is between 2°C and 16°C (35°F and 60°F). If you have too much ice then you risk an injury from frostbite. if your water is above the 16°C threshold then your body doesn’t e.g. increase noradrenaline production. I consider 10°C (50°F) to be a sensible target.
The Easiest Way to Decrease Temperature is to swirl the water around periodically. As you bathe in cold water, you heat up the water closest to you. When you swirl the water you replace it with colder water from elsewhere in the bath.
The Physics of the Ice Bath Calculator
To melt 1kg of ice, a large amount of heat energy is required – called the Latent Heat of Fusion. This amount of energy is the same as the energy required to heat 1kg of water by 80°C!
Furthermore, when water (e.g. melted ice at 0°C) is mixed with water at another temperature, the resulting body of water has a temperature calculated as the weighted average.
The formula used by this calculator is therefore:
Final Temperature × (Water Volume + Ice Volume)
EQUALS
Ice Temperature × Ice Volume + Water Temperature × Water Volume – 80 × Ice Volume
Further information
This calculator was written by Daniel Timms – you can contact me here.
This calculator was created in 2019 as a resource for people interested in cold baths (and possibly Physics teachers!) In April 2022, the nice people at PLUNGE provided me with affiliate links for this page (marked with an asterisk*) so that when you purchase a PLUNGE product via these links, they can thank me with a small commission that helps fund this site. The price you pay is the same—or actually less, if you use the coupon suggested!